Highest 24-Hour PM2.5 Concentration
PM2.5 is very fine particulate matter, 2.5 micrometers and smaller. This indicator measures the 3-year running average of the 98th percentile 24-hour average concentration of PM2.5. The highest PM2.5 concentrations in Tahoe are associated with wildfires. Particulate matter less than or equal to 2.5 microns in size (PM2.5) is associated with a variety of human health concerns, including asthma, lung diseases, and heart disease. The primary sources of PM2.5 in the Tahoe Basin are residential fuel combustion, campfires, wildfires, prescribed fires, motor vehicles, and dust from unpaved roads. PM2.5 is monitored by TRPA and partners at three sites around the Basin.
Status
PM2.5 monitored in the Tahoe Basin from 1990 to present.
Evaluation Map
The location of air quality monitoring stations in the Lake Tahoe Basin. PM2.5 is monitored by TRPA and partners at three sites around the Basin.
2019 Evaluation
- Status
- Considerably Better Than Target
- Trend
- Moderate Decline
- Confidence
- High
Applicable Standard
AQ11: Maintain Particulate Matter2.5 at or below 35µg/m3 measured over a 24-hour period using gravimetric or beta attenuation methods or any equivalent procedure which can be shown to provide equivalent results at or near the level of air quality standard.
Key Points
- The Tahoe region continues to enjoy high air quality. The highest reading at any site was 60% of the threshold standard value.
- The increasing extent and severity of wildfires is likely contributing to the increasing trend in peak PM2.5 concentrations. The highest 24-hr concentration of PM2.5 is heavily influenced by wildfires. In years where wildfire smoke is blown into the region, the highest 24-hour concentrations of PM2.5 spike.
Delivering and Measuring Success
EIP Indicators
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Miles of Street Sweeping
Since 2009 EIP partners have swept more than 61,000 miles of roadways within the Tahoe Basin reducing fine sediment particles from roadways entering the air and water.
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Non-Compliant Wood Stoves Removed or Retrofitted
This EIP performance measure tracks removal of polluting wood stoves to reduce local air pollution for human and ecosystem health.
Example EIP Projects
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Lake Tahoe West Landscape-Scale Restoration Partnership
Projects to improve forest health and thus prevent or reduce wildfire intensity such as the Lake Tahoe West Landscape-Scale Restoration Partnership will help decrease high particulate matter days.
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Spooner Hazardous Fuel Reduction & Healthy Forest Restoration
This project, completed in 2018, included hazardous fuel reduction and forest ecosystem health treatments on approximately 3,100 acres of the east shore of the Lake Tahoe Basin.
Monitoring Programs